Lingering Effects of First Debate Almost Gone

According to tonight's FiveThirtyEight forecast, or the most recent version of it in any case, Barack Obama has an 83.7% chance of winning Tuesday's Presidential election. The last day on which he had a higher chance of victory was October 5th, at 84.9%, a very similar state of affairs. The day before that, October 4th, was Obama's highest odds of victory ever, at 87.1%. The day before that, October 3rd, was the date of the first Presidential debate in Denver, Colorado, which essentially everyone thought Obama lost. Obviously, the October 4th forecast didn't yet reflect Obama's decline, as the polls released that day didn't include any post-Denver interviews. But starting on the Fifth, Obama plummeted, dropping all the way down to a measly 61.1% chance of winning on October 12th. But the Vice Presidential Debate, on October 11th, was seen as a win for Obama's running mate, Joe Biden, and Obama won the second and third Presidential debates rather handily, and ever since the 12th of October he's been inching his way back up in the forecast. For a while this had looked like basically a point a day, though it's accelerated of late. Long story short, Obama has clawed his way back to roughly the same odds of victory that he had after Romney's debate victory had only been processed by the polls for a single day. One more good day of polling tomorrow could easily get him back to his highest victory odds yet.

Of course, that's just the "percent chance to win" forecast. Since we've gotten a lot closer to Election Day, the implicit margin of error in the forecast has gone way down, so the actual margin that's giving Obama these same odds of winning as on October 5th is much smaller than the margin he held on that date. Specifically, right now he's projected to win 305.3 electoral votes, and to win the popular vote by 2.2%, numbers which shift just slightly to 306.3 and 2.3% if you switch from the forecast to the now-cast. On October 5th, Obama was forecast with 317.7 electoral votes and a 3.9% popular-vote margin, and had a 4.7% lead that equated to an average of 327.7 electoral votes in the October 5th now-cast. So Obama's margin has been declining in more or less lock-step with what I like to think of as the cone of declining uncertainty. (Visualize the lines from any point on the electoral-vote or popular-vote forecast graphs at date X to the point that would, if it were the November 6th forecast, give the same odds of victory. If you do this for the leading and the trailing candidate from the same date, it's a cone.)

Still, the fact remains that Mitt Romney is very close to having failed to increase his odds of winning this election over the last month, including what was by far the best night of his political life.